Virgin systems can also tell, within a certain distance, whether equipment is being used in the area it is registered to operate. Move the kit to an area controlled by a different optical node & unless an account address change is registered it gets disconnected.
In other words, only equipment on YOUR account (which only you can alter) is registered at YOUR address. If he starts using equipment registered at another address he will still be paying for it at the old address, but is likely to find it ceases to work after a few days.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV+), Talk Unlim Telco, VIVID 100, Virgin PAYG Mobile